Telephone-exchange system.



No. 649,868. Patented ay I5, I900.

W. D. GHARKY.

TELEPHQNE EXCHANGE SYSTEM.

(Application filed Apr. 21, 1899.) (No Model.) 2 Sheets-Sheet I.

m: NORRIS versus cc, umaurwo. WASHINGTON DV 0.

Nu. fi wfififl. Patented May I5, 1900.

W. I]. GHARKY.

TELEPHGNE EXCHANGE SYSTEM.

(Application filed Apr. 21, 1899.) (Ho ModaL) 2 Sheets$heet 2,

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\VILLIAM D. GIIARKY, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO THE SUNELECTRIC MANUFACTURING COMPANY, OF NE\V JERSEY.

TELEPHONE-EXCHANGE SYSTEIVl.

srnczrronrion forming part of Letters Patent No. 649,868, dated May 15,1906.

Application filed April 21, 1899. Serial No. 713,880. (No model.)

T (0 whom it 72mg concern:

Be it known that 1, WILLIAM D. GHARKY, a citizen of the United States,residing in the city of Philadelphia, in the county of Philadelphia andState of Pennsylvania, have invented a certain new and usefulImprovement in Telephone-EXchange Systems, of which the following is aspecification, reference being had to the accompanying draw- IO ings,forming a part hereof, in which the same letters and numerals ofreference point out the same parts throughout.

My invention relates to telephone exchange systems, and particularly tosystems I 5 wherein each subscriber has but a single lineterminal andconnection between subscribers lines whose terminals are not upon thesame board-section is effected through the agency of trunk or transferlines. I have found it expedient in such cases to localize theresponsibility for the through connection as much as possible, and forthat purpose the answering operator is required to perform all of thework incident to a complete connection except the actual connection anda disconnection of the trunk or transfer plug. Such localization ofresponsibility requires that the answering operator shall have a meansof supervising as well as controlling each step of the connection. It isthe direct object of this invention to furnish such a supervisory meansof improved arrangement and design.

In attaching signals to telephone-circuits it 3 5 is frequently foundconvenient to employ ground-taps, and part of this invention dependsupon the use of such ground-taps; but as grounds upon telephone-linesare always objectionable and are liable to cause trouble duringconversation according to this invention all grounds are removed fromthe lines during conversation.

Referring to the accompanying drawings, Figure 1 is a diagrammaticrepresentation of two telephone-stations connected with central station,together with the apparatus for interconnecting the lines. Figs. 2, 3,and 4 are similar representations of certain modiiied circuits andapparatus.

In Fig. 1, X and Y are two subscribers stations connected, respectively,at the central station to spring-jacks J and J. In proximity to thespring-jacks annunciators A and A are connected each in a bridge 10across its pair of line-wires. The apparatus at the two subscribersstations is exactly the same in every respect, and the parts arelettered the same, with the exception of exponents, so that thefollowing description of station X will suffice for both.

The line-wires 1 and 2 terminate at the subscribers station in twomovable members of a switch-hook S 8. These two members are mechanicallyconnected by a piece of insulating material or by an insulated piece ofany sort, so as to move together. The member S carries the usualbifurcated support for a telephone-receiver It, the weight of which isadapted to move the entire switch in one direction, While a suitablespring is arrangedto move it in the other direction when the receiver isremoved. When the receiver is upon the hook, the latter rests upon acontact 3 its other members resting upon a contact the contacts 3 sforming terminals of a circuit 5 6, containing a hand-generator G and aringer Q. The generator is provided with the usual shunt connection 8.

When the hook-switch rises, the line-wires are disconnected from thecircuit 5 6 and through contacts 3 and s are brought into. connectionwith circuit 3 at, containing the receiver R and the secondary winding2' of the induction-coil I. At the same time the switch member 5, makingcontact with the terminal 5 closes the local circuit at 9, containingthe transmitter T, the local battery t, and the primary winding t" ofthe inductioncoil.

The middle point of the windings of each 0 ringer Q Q'is connected bywire 7 to ground. It should be noted, however, that when the receiversare off the hooks and conversation is going on these grounds are not inany way conneoted with the line.

At the central station connection between subscribers lines whoseterminals are upon the same board is directly effected by means of apair of plugs P and P, forming the terminals of a cord-circuit 11 12 13let. This cirzoo cuit is normally completed through anvils 7t" andsprings 7.; of a ringing-key K, the dcprcssion of whose button, however,is adapted to separate the springs from the anvils and cause them toimpinge upon terminals 9 of the circuit 21 21 of a calling-generator GIt will be observed that by such operation the answering-plug and thecalling-line receive no current, but that the calling-plug is connectedto the generator.

Bridged across the conductors 13 14 is a wire 17, forming the terminalsofequalwindings on an impedance-coil O. The middle point of thesewindings is connected by a wire 18 to a lamp L and thence to a magnet mby wire 19, to a magnet m to and through the contact an and armature mand by wire 20 to battery B and to ground. The armature m is normallyheld up against the contact m by a hook m on the end of an armaturem,which is under the control of the magnet m and is pivoted at itsopposite end, so that it is retracted from the magnet by gravity alone.The armature m on the other hand, is adapted to be retracted from themagnet m by a spring m and in order to make the action of the armaturequick and sensitive the spring is given some tension and is located' soas to produce a pull directly opposite to that of the magnet.

The apparatus thus far described is sufficient for interconnection oflines on the same board; but for lines located upon different boardstrunk-lines are employed, each having a jack J 2 at the answering-boardand a plug P at the calling-board, connected with each other byconductors 15 16.

The description of the operation will be confined to a trunk or transferconnection, as connection upon one board is the same, omitting thetrunking.

Supposing that subscriber X desires to converse with subscriber Y, hefirst operates his generator Or and then removes his telephone from thehook and awaits a response. The current from the generator rings his ownbell and also throws down the drop of the annunciator A at central. Theanswering operator, perceiving the signal, restores the drop and insertsplug P in jack J, at the same time asking the number wanted. I have notshown the 'operators circuit nor the instruction-circuit betweenoperators, as these are of any suitable and well-known type and it"shownwould unnecessarily complicate the drawings. Having ascertained thenumber required to be Y, the operatorinserts the plug P into the jack Jof a trunk-line leading to Ys board. At the same time if the armature mof the magnet m is not in the position shown in Fig. 1 the operatorplaces it so. The number is communicated by the answering operator tothe trunk operator at the other board through the usualinstructioncircuit, whereupon the trunk operator inserts the plug P intothe jack J of the wanted line. As soon as this connection is made acircuit is'completed for the main batteryB as follows: By wire 20 toarmature m contact m magnet m wire 19, magnet m, wire 18, lamp L, andwire 18 to and through the windings in parallel of the impedance-coil C,by

wire 17 to conductors 13 14, and thence through the two sides of thetrunk-line in parallel and through the line-wires 1 2 of the wanted linein parallel to switch members S .9, wires 5 '6, shunt 8, windings inparallel of [the ringer Q, and wire 7 to ground and back to battery. Itmust be observed that the ground being on a subscribers line only whenhis hook-switch is depressed the calling subscriber having his telephoneoif the hook affords no path for this current. The flow of current inthis circuit from battery B causes the lamp L to glow and both mag netsm and m to attract their armatures. The answering operator perceivingthe lamp L to glow knows thatthe line is connected clear through andproceeds to depress the button of the ringing-key K to throwcallingcurrent thereupon. This current passing over the metallic circuitactuates the ringer Q. Subscriber Y, answering the call, removes thereceiver R from his hook, whereupon the latter rises, closes his lineand local talking circuits, and simultaneously throws off the ground.This breaks the circuit that previously existed for current from batteryB, and both magnets m and m are therefore deenergized at the sameinstant and the lamp L is extinguished. magnets start to retracttogether; but the armature m moves more quickly by reason of its spring,(the other armature being influenced solely by gravity,) and thereforegets outside of the hook m before the latter has descended far enough torestrain it. The circuit from ground through the battery B to line isthus interrupted between armature m and contact m and so remains untilthe subscribers have finished their conversation and rung ofl, whichthey accomplish by hanging up their receivers and again energizing themagnets of the annunciators A and A.

Figs. 2, 3, and 4 illustrate modifications of the system thus described,whereby the impedance-coil C is done away with, and instead of the wire18 being connected thereto it is adapted to be prolonged to the middlepoint of the windings of one of the line-annunciators.

In Fig. 2 each annunciator A has a wire 22 taken oiffrom the middlepoint of its winding and connected to a third contact in the jack, shownas a thimble j. The answeringplug is here provided with three contacts19, p, and 29 The first two make contact with the ordinary jack-springsand the last cooperates with the contact-thimble j and is the terminalfor the Wire 18. The operation in this case is precisely the same asbefore, the annunciator A constituting an impedancecoil and its locationbeing a matter of indifference as long as it is bridged across some.portion of the through-circuit. There is one diiiieulty, however, to beovercome, which is The armatures of the two that with the apparatusshown in Fig. 2 when the trunk-plug has been inserted and the magnets mand m have attracted their armatures the operation of the ringing-keywill break the ground-circuit, and thereby cause the armatures toretract and a false signal to be given. To overcome this, theconstruction shown in Fig. a has been designed. Here the spindle of theringing-key is provided with a projection which when the ringing-key isdepressed passes behind the upper end of the armature m and holds thesame up until the hook m again engages it. Another way of overcomingthis difficulty is shown in Fig. 3, where the wire 18 is connected tothe third contact 13 on the plug P and is prolonged through a thimblejin the trunk-jack J and a third conductor 23 in the trunk-circuit to asimilar contact 011 the trunk-plug. All of the lines are provided withthimbles jj, connected by wires 22 to the middle point of thelineannunciator windings. It will be observed that by this method ofconnection the wire 18 is put to line between the called subscriber andthe ringing-key, and hence can never be cut off by the latter from theformer.

Having thus described my invention, what I claim, and desire to secureby Letters Patent, is-

l. In a telephone-exchange system, a subscribers station and a centralstation, and a line connecting the two, a connective circuit at thecentral station, a signal-circuit,a switch normally maintaining the samein connection with the connective circuit,amagnetincluded in saidsignal-circuit and controlling the switch, and a generator connectedthereto, together with a branch from the other side of said generator tothe subscribers station where it is normally, while the apparatus is indisuse, maintained in connection with the subscribers line, and meanscontrolled by the subscriber for disconnecting the generator branch fromhis line, substantially as described.

2. In a telephone-exchange system, a central station, subscribersstations, and circuits connecting each subscribers station with thecentral station, connective circuits at the cen tral station, asignal-circuit for each connective circuit normally connecting thelatter through a generator to ground, a supervisory signal therein, aswitch for the signal-circuit, a magnet controlling the switch andincluded in said circuit, and a ground-tap at each subscribers stationnormally in connection with his line-circuit, and adapted to completesaid signal-circuit on the completion of a connection, but adapted to bedisconnected therefrom when the line is switched for conversation,substantially as described.

3. In a telephone-exchange system, a centralstation, and subscribersstations connected therewith by lines terminating in spring-jacksthereat, connective cord-circuits terminating in plugs to interconnectsaid jacks, a signal-circuit for each cord-circuit,

with a switch for holding the same normally connected thereto, a detentfor said switch to hold it closed, the switch being adjusted to retractquickly when released, and the detent being adjusted to move sluggishly,a pair of magnets included in the signal-circuit and controlling theswitch and detent respectively, a grounded generator connected to thesignal-circuits, and a ground-tap at each subscribers station normallyconnected to his line-circuit, but adapted to be disconnected therefromwhen the line is switched for conversation, substantially as described.

4. In a telephone-exchange system, a central station, subscribersstations, and lines connecting the latter with the former, connectivecircuits and a signal-circuit for each connective circuit with a switchnormally completing a connection between the two, and a detent forkeeping said switchclosed, a pair of magnets in each signal-circuit,both acting simultaneously, one to remove the detent from the path ofthe switch and the other to hold the switch as long as thesignal-circuit remains intact at other points, and means at eachsubscribers station for breaking the signal-circuit when its connectivecircuit is attached to his line, substantially as described.

5. A switch for supervisory signal-circuits consisting of a movablemember forming a part of the circuit, relatively-fixed members, a detentfor maintaining the movable mem bers in closed relation with said fixedmem bers, a pair of magnets in series with the switch-contacts, onemagnet controlling the movable member and the other controlling thedetent, substantially as described.

0. In a telephone-exchange system, a central station, subscribersstations and circuits connecting the former with the latter, connectivecircuits at the central station, a signal-circuit normally joined toeach connective circuit, having a branch entering each subscribersstation and there normally com pleted through his line, but interruptedat the central-station terminal thereof, means controlled by theoperator in eiiecting con nection with a line to complete the entiresignaling-circuit and means under the control of the subscriber forthereafter breaking the same, substantially as described.

7 I11 a telephone-exchange system, a central station, subscribersstations, and linecircuits connecting the latter with the former,connective circuits at the central station, a signal-circuit connectedfrom each connective circuit to a generator and ground, a normallyclosed switch included in said signal-circuit and a magnet also in saidcircuit adapted to hold the switch closed as long as the circuit remainsintact at other points, and a groundtap at each subscribers stationnormally connected to the subscribers line-circuit, but adapted to bedisconnected therefrom by the act of switching a line for conversation;whereby when an operator makes connection with a line the signal-circuitwill beclosed, 'my hand, in the presence of two witnesses, and when thesubscriber responds by switchthis 18th day of April, A. D. 1899. ingtheline for conversation the signal-cir- 'cuit will be broken, andthereafter the line 5 will remain free from grounds, substantiallyVitnesses:

as described. ANDREW V. GROUPE,

In testimony whereof I have hereunto set EDWARD E. CLEMENT.

WM. D. GI-IARKY.

